The present invention relates to a drive apparatus for a flexible record carrier, in particular, for a magnetic disc enveloped in a flat envelope having a central hole through which a central portion of the disc is accessible for driving engagement during operation.
Such an apparatus includes a frame having an entrance opening adapted for receiving an enveloped disc, a pivoted cover having a front and a rear side and arranged on the frame for movement between an open and a closed position, a turntable rotatable about an axis of rotation, a first stationary member forming a portion of the frame located at the clamping member side of the disc, a second stationary member, for locating the turntable, and forming a portion of the frame located at the turntable side of the disc, a guide spindle mounted in the first member and being coaxial with the turntable, a rotatable clamping member movably mounted on the spindle for axial movement therealong, and linking means for moving the clamping member toward and away from the turntable. The linking means is arranged between the cover and the clamping member to cause a received disc to be clamped between the clamping member and the turntable when the cover is closed and to be unclamped when the cover is open.
From U.S. Pat. No. 4,216,510 a drive apparatus is known in which the cover together with a roller and clamping-lever linking mechanism as well as with the lifting part of the drive mechanism including its spindle constitute an interchangeable assembly connected to the rest of the apparatus as a unit. The pivotal axis of the cover is situated at the upper edge so that, after opening, the cover projects completely from the drive apparatus and impedes the insertion and removal of the flexible record carrier. Furthermore, the roller connected to the cover is arranged so that, in any operating position of the cover, it is positioned on the upward slope of the clamping lever and is moved only slightly on said slope. In order to ensure that the record carrier is correctly centered and is firmly positioned in the drive mechanism, the lifting part of the drive mechanism is formed as a cone and is urged against the stationary part by a compression spring compressed by the clamping lever. Because this spring force is comparatively great, the clamping lever must also exert a comparatively great force on said spring. As a result of this, a continuously increasing pressure must be exerted on said cover when it is to be closed. Therefore, the cover must be of very stable construction. Moreover, such a drive apparatus cannot be incorporated in light-weight equipment because this equipment would slide away when the cover was closed if no counteracting force were exerted on the equipment. Furthermore, because of the separation between the spindles of the two parts of the drive apparatus, it is not unlikely that these spindles will not be in line (not precisely coaxial) owing to manufacturing tolerances or wear effects. This non-coaxiality may impair the correct retention of the flexible record carrier.
Furthermore, a drive apparatus is known from U.S. Pat. No. 3,940,793, in which the cover comprises a lever with a downwardly curved slope which, upon actuation of the cover, runs between two rollers of the clamping lever and then pivots said lever about a pivotal axis. This known drive apparatus is very intricate. The cover as well as its lever cannot be made comparatively thin and thus cannot be manufactured in a simple manner, because, although the clamping lever does not act on a compression spring, the total pressure for clamping the record carrier in the drive mechanism is produced by the lever of the cover. Thus, the force required for closing the cover will also steadily increase with this construction.